Authority: Terror inspires another exception to the principle of keeping soldiers out of domestic issues.

WASHINGTON - Despite a 124-year-old law that largely bars the military from domestic law enforcement, a wide spectrum of legal experts and members of Congress support the Pentagon's becoming involved last week in the search for the sniper responsible for killing people in Maryland, Virginia and Washington.

Several lawmakers and experts on the 1878 Posse Comitatus Act said the military is acting within a limited scope of authority that is permitted during crises under subsequent revisions to the law.

Some civil libertarians in Congress remain wary, however, about using the armed forces for future anti-terrorism work.

Defense Secretary Donald H. Rumsfeld signed an authorization Tuesday that allows military RC-7 reconnaissance planes equipped with high-tech night vision sensors to help law enforcement officials track the sniper. The technology exceeds what police had.

"Rumsfeld did the right thing in accommodating the need for this technology," said Sen. Dianne Feinstein, a California Democrat who chairs the Senate Judiciary Committee's panel on technology and terrorism. "I'm doubtful we need to make a change in the [Posse Comitatus] law. After all, we never know whether this is something coming from outside or inside, or part of a terrorist effort."

Sen. Jon Kyl of Arizona, the technology and terrorism panel's top Republican, agreed: "We all support the current law. The military knows full well how to make it work and not overstep its bounds."

Post-Civil War law

The original 1878 law was passed with the intent of removing the Army from domestic law enforcement. After the Civil War, troops were used extensively throughout the South to maintain order at political events and polling places, prompting complaints from some in Congress that they were intimidating voters and straying too far from their original mission of national defense.

Within the past two decades, however, Congress has clarified several times that the armed forces can provide logistical or backup support to police. One of the changes came in 1981 after the FBI called in military advisers to deal with violent uprisings on Indian reservations.

Behind the scenes

"When you put up a military plane with a cop with a set of binoculars, that follows the line that Congress laid down in 1981 between direct military participation and logistical support," said retired Army Gen. Joseph R. Barnes, a lawyer and expert on the Posse Comitatus law.

"It wouldn't surprise me if part of the military's assistance is to analyze the behavior [of the sniper] and the terrain and techniques and say that based on their analysis, `He's likely to strike here.' That wouldn't violate the act, either. Behind-the-scenes advice and logistical support are consistent with the technical issues in the act."

The Cato Institute, a libertarian Washington think tank that fashions itself as a watchdog of governmental power plays, held a panel discussion Wednesday on the Posse Comitatus Act. No one on the four-person panel called the military's role in the sniper case a violation of the act.

"If by that process we can find the madman, or madmen, it's a marvelous example of military-civilian cooperation, quite in keeping with the Posse Comitatus Act," said Paul Schott Stevens, a former legal adviser to the National Security Council under President Ronald Reagan who now practices in the Washington office of Dechert, an international law firm.

"There are few of us in Washington who would say we don't want the DOD [Department of Defense] involved."

`All in the open'

Stephen P. Halbrook, an author and attorney based in Fairfax, Va., said that unlike some uses of the military in law enforcement cases - such as the 1993 attack on the Branch Davidian religious compound in Waco, Texas - the government's use of surveillance in the sniper case is "all in the open," as it should be.

"This is not something I oppose, even though I'm a stickler for strict enforcement of the Posse Comitatus Act," Halbrook said.

Under the act, the military also is permitted to assist law enforcement by providing intelligence on drug trafficking and during emergency situations involving biological or chemical weapons.

Still, the issue of whether soldiers should be given a greater hand in countering terrorism on U.S. soil has been debated for years.

Sen. John W. Warner of Virginia, the Senate Armed Services Committee's top Republican, said he has tried since Sept. 11 last year to get Congress to take a broader look at strengthening the military's domestic terrorism responsibilities.

"Every asset in America - whether it's the policeman on the street corner or the general sitting at the Pentagon - if they can bring some expertise to stop terrorism here at home, it should be done," said Warner, who plans to meet with Rumsfeld to further discuss how Congress and the Pentagon can help catch the sniper. "It's a changed world."